OK, let's do this. We've got 9869 and 10 and we're adding them all together.

Step 1: We'll start by adding the digits 9 & 0 in column 1 and get 9.

Step 2: We'll start by adding the digits 6 & 1 in column 2 and get 7.

Step 3: We'll start by adding the digits 8 & 0 in column 3 and get 8.

Step 4: We'll start by adding the digits 9 & 0 in column 4 and get 9.

So, 9869 + 10 = 9879.

